Photoflash lamp



N. C. BEESE PHOTOFLASH LAMP Sept. 8, 1953 Filed June 27, 1951 gli. of

Tam/Mz Marmara@ INVENTOR 13 /v. c'. 55252'. ma w' 'rorz Patented Sept. 8, 195.3

Norman C. Beese, Veron a, N. 4assignor to West--k inghouse Electric Corporation, East Pittsburgh,

Pa., a corporation oi' Pennsylvania Application June 27, 1951, serial No. 233,875

4 Claims.

My invention relates to photoilash lamps and, more particularly, to such Ain which the light output is furnished chiefly by combustion of primer material.

Photoilash lamps are made with a combustible material therein which upon being heated is ignited and burns toV produce a ilash of light. Heretofore, the combustible material or primer mass which was used has been in the form ofl a paste around the filament supports; and there has been, after flashing-the lamps, a residue of unburned combustible material that adheres to the metal supports. I have found that this material did not reach the kindling temperature because of the cooling effect of the metal support wires.

Therefore, an object of my invention is to provide an improved photoash lamp.

A further object of my invention is to effect more complete combustion of the primer material within photoilash lamps.

Another object of my 'invention'is to provide a photoi'lash lamp having afgreater light output.

Still another object of my invention is to provide a photoflash lamp whose ilash is of increased time duration.

Yet another object of my invention is to provide a photoilash lamp wherein the primer mass is supported by a poor thermal conductor.

More specifically, an object of my invention is to provide a thermal insulating coating between the primer within the photoflash lamp and its support.

The novel features that I consider characteristic of my invention are set forth with particularity in the appended claims. The invention itself, however, together with additional objects and advantages thereof, may be best understood from the following `description of specific embodiments when read in conjunction with the accompanying drawing in which:

Figure 1 shows a photoiiash lamp in side elevation.

Figure 2 is a vertical sectional view on an enlarged scale, axially of the lament supports of the lamp.

Figure 3 is a cross sectional view of one filament support, on a still larger scale.

One type of photoflash lamp, commonly made has a combustible material therein called a primer which, when subjected to heat, ignites spontaneously with a violent exothermic chemical reaction to produce a ash of light for a short duration of time. A photoash lamp I is shown generally in Figure 1, which lamp has a re-entrant stem I2 sealed into one end of its envelope I4. Sealed through the stem I2 and extending into the lamp I 0 are two meta1 Wire lament supports I6. These supports also function as lead-in conductors to filament I8, preferably of tungsten, which is supported therebetween. The lead-in conductors I6 are connected to acup-shaped base I9 which is cemented to the lamp envelope I4 at the stem end thereof. One of the lead-in conductors I6 is connected to the metal shell 20 of the base I9 while the other lead-in conductor is connected to a metal button'2l: in the bottom of theV base, which button is insulated from the shell 20. The shell of the base and the metal button constitute the two outside. terminals for supplying power to the filament I8. The lamp envelope is lled with a combustionsupporting gas, such as oxygen, at a pressure of approximately mm. of mercury.

It hasl been'the practice in the past to apply a-coating ofcombustible material, known as the primer, around `the lament end of the lament supports. The primer may be zirconium powder contact with its support. To do this I provide on the llament end of the su'pport I6 a thermal insulating coating 22 on the top of which is the primer material 24, as is best shown in Figures any suitable substance such as silica, alumina or talc. As pointed out above, the insulator may be applied to the supports I6 in the form of a coating. This coating may be applied to the supports by dipping them into the insulating mixture in the form of a viscous paste which comprises the insulating material in powdered manner. The primer mass is the sole source of light within the lamp.

In operation, radiant heat from the incandescent tungsten wire lament I8 raises a small section of the primer to its ignition point which causes a reaction that spreads through the en- As pointed out above, the thermal conductivity of the support wires, if no insulatduration. The peak light intensity remains apr-1 proximately the same, as Well as the time td.

initiate the ignition, and the length of timetoV peak light output. Therefore,Ihavelengthenedf the duration of the flash by efiectin'ga more com. plete combustion of the primer material, and

have thereby increased the light. output. oi; the;V

lamp for a given amount of combustible material.

The essence of my invention lies in supportingthe primer mass on a body which is a poor thermal4 conductor, thereby. assuring` .combustion ot the: entire mass. 'Ihcmethod osuppontingz-theprimer as. outlined above. is. preferred since; itz. is simple. and inexpensive. While `the above; der. scription has. been directed tow-arda.- photofiash lampfwherein the light furnishedsolelyf by the. primer mass, the thermal;insulatorv not beingoxidizedg. the :invention itself f isnnot; so. limited' and' may also. be applied; to: any type: of photoash lamps: where itv is' desirabletofefiect betten combustion. of the primer/mass,

It. will. be readily: seen; from the: above that: I' have provided animproved photoflashglamp have ing increased. light` outputl andreiliciencyv as. a result` of improvedcombustion oftherfprimer maf terial: resulting a ash, of. longerV` time. dura-,- tion.

WhileV IV have shown and; describeda specific embodiment of my invention, I am; fiillyaware that many modifications thereof. are possible... I donot intend to be restrictedA therefore,` exceptas is necessitated; bythe scope: and'. thea spirit. i of' the appended. claims.

I claim:

1. A photoash lamp having a light transmitting envelope and a pair of spaced metal supports therein, a, thermal insulating coating on said supports, a primer coating supported by said insulating coating whereby said primer coating is prevented from direct contact with said suppor-ts, an incandescent filament.. bridging said supports and adapted toheat part-,of said primer mass to ignition temperature, and a combustion 'supporting gas within said envelope.

2.. Aphotoflash lamp comprising a light trans- -mitting envelope and having combustible materiali'therein.tofberoxidized for the production of alight, 'meansstofignite said material, a metallic supportlforsaid material, and a thermal insulatorbetweenlsaid material and said support.

"3. A photoash lamp comprising a light transmitting envelope and having combustible material therein, a filament adapted to heat said materal^ ahcatconductivesupport for. said materiale. anda a; thermalinsulator between said. mate.-`

rialfand said` supporta y 4. A photoiiash lamp comprising a lighttransmittingf-envelope: and` having combustible. materialtherein-isfthe solesource of light, a lament adapted.v to lheat; said, material. tol cause oxidafE tionfthereof, a-metalsupportfor both said mate.- rial-andf said` lament, andiathermal insulator. between said material. and said support.

NORMAN C IBEESE.

" References- Gitedl lill' the-1 A fil Offthisf. patent.

' unrr'an'sfiltras PATENTS.- 

